Docs: Consistently document the $body_id global as a string.

Includes declaring the global at the beginning of `wp_iframe()` and `iframe_header()`.

Follow-up to [32642], [32643].

Props mukesh27, upadalavipul.
Fixes #60032.

git-svn-id: https://develop.svn.wordpress.org/trunk@57181 602fd350-edb4-49c9-b593-d223f7449a82

src/wp-admin/includes/media.php

@@ -527,12 +527,14 @@ function media_handle_sideload( $file_array, $post_id = 0, $desc = null, $post_d
  * @since 5.3.0 Formalized the existing and already documented `...$args` parameter
  *              by adding it to the function signature.
  *
- * @global int $body_id
+ * @global string $body_id
  *
  * @param callable $content_func Function that outputs the content.
  * @param mixed    ...$args      Optional additional parameters to pass to the callback function when it's called.
  */
 function wp_iframe( $content_func, ...$args ) {
+	global $body_id;
+
 	_wp_admin_html_begin();
 	?>
 	<title><?php bloginfo( 'name' ); ?> &rsaquo; <?php _e( 'Uploads' ); ?> &#8212; <?php _e( 'WordPress' ); ?></title>
@@ -603,8 +605,8 @@ function wp_iframe( $content_func, ...$args ) {
 
 	$body_id_attr = '';
 
-	if ( isset( $GLOBALS['body_id'] ) ) {
-		$body_id_attr = ' id="' . $GLOBALS['body_id'] . '"';
+	if ( isset( $body_id ) ) {
+		$body_id_attr = ' id="' . $body_id . '"';
 	}
 
 	?>

src/wp-admin/includes/template.php

@@ -2118,14 +2118,17 @@ function _admin_search_query() {
  *
  * @global string    $hook_suffix
  * @global string    $admin_body_class
+ * @global string    $body_id
  * @global WP_Locale $wp_locale        WordPress date and time locale object.
  *
  * @param string $title      Optional. Title of the Iframe page. Default empty.
  * @param bool   $deprecated Not used.
  */
 function iframe_header( $title = '', $deprecated = false ) {
+	global $hook_suffix, $admin_body_class, $body_id, $wp_locale;
+
 	show_admin_bar( false );
-	global $hook_suffix, $admin_body_class, $wp_locale;
+
 	$admin_body_class = preg_replace( '/[^a-z0-9_-]+/i', '-', $hook_suffix );
 
 	$current_screen = get_current_screen();
@@ -2179,10 +2182,7 @@ function tb_close(){var win=window.dialogArguments||opener||parent||top;win.tb_r
 	?>
 </head>
 	<?php
-	/**
-	 * @global string $body_id
-	 */
-	$admin_body_id = isset( $GLOBALS['body_id'] ) ? 'id="' . $GLOBALS['body_id'] . '" ' : '';
+	$admin_body_id = isset( $body_id ) ? 'id="' . $body_id . '" ' : '';
 
 	/** This filter is documented in wp-admin/admin-header.php */
 	$admin_body_classes = apply_filters( 'admin_body_class', '' );